Issues with batteries after replacing gears

Had finally chewed original gears an pinion head with sons ACR. After replacing them greasing gears cleaning gearbox etc. An putting all back together no longer runs on 7.4v battery but shoots fine an probably better on the 11.1v I have an used with ACR B4 even though to big to fit in blaster. Any ideas why? Not big concern but just hate not knowing why!! Can take some vids to show an hear noise. Even sounds like battery not powerful enough to run motor. Yet original motor. An tested same battery on my new gen 9 m4 an battery worked fine.

My first check would be shimming with an expectation of rubbing or too tight.

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As @zeHamish says shimming.
Your pinion to bevel mesh is not set correctly or you have something too tight.

It actually sounds better to shoot with an doesn’t sound like shit like it did when it would run on the 7.4v. Which gets me as well. But cool the bloke I get to work on my blasters when I get stuck an shows me where I’ve gone wrong said it might need shimming…so noob question what does shimming do? If I don’t ask I wont know. An shout out to the awesome vids low guido makes as helped me learn alot already an rest of u guys rattler who have answered alot of my noob as questions.

Shimming removes the end float on all the gears (The up and down movement) you still need a very tiny amount so all the gears spin freely.
Shimming also sets the pinion to bevel mesh.

Cool. So basically stops rattle in the gears an adjusts pinion head yeah

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Yes basically, it sounds easy but it’s not !
Patience and some knowledge is required so if your mate could guide you, take him up on it :wink:

I also wouldn’t continue to use it until it is checked because you can damage the gears very quickly

Yeah havnt done just in case that would happen. Between myself an his brothers have spare blaster for me eldest son to use while his outa action

Oh btw did you replace the gears with the stock ones or metal ?
Also did you replace the pinion ?
If you did replace the motor pinion , did you put it on at the exact same position as it was before ?


This will help you
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Cheers heaps mate. I’ve been learning how to upgrade my blasters myself an be able to fix them. An welcome the help.

Just replaced pinion head an the first gear with new nylon ones for the time being. Have my sons ACR, my m4 an vector all to fully upgrade so yeah. When go to metal gears will be when I do complete upgrade on them.

If that’s all you did and you didn’t adjust the motor height I would remove the grip base and check you haven’t got any wires in the way of the base where it seats on the motor because it pushes the motor too far in.

Yeah already done that was first thing made sure was right b4 screwing in place

Their no adjuster in plate to adjust motor like the m4 has